Project Summary Myologica is a small business focused on developing therapeutics for neuromuscular diseases. Started in collaboration with the University of Maryland, Myologica maintains a vigorous in-house pre-clinical discovery program in Duchenne Muscular Dystrophy (DMD) while providing consultation and specialized neuromuscular function testing for non-profit and corporate clients. The objective of this proposal is to demonstrate the feasibility of our novel therapeutic strategy, developed through years of expertise and careful research, to slow the progression and reduce the severity of DMD. DMD is the most common X-linked neuromuscular disease, affecting approximately 1 in 2500 male births in the US. Although the genetic basis for this deadly disease is known (lack of dystrophin), there are currently no cures. At Myologica, we have identified the disease-altered microtubule network as a novel therapeutic target in DMD and that acute treatment with colchicine can prevent muscle and cardiac injury during stress. Despite growing evidence for the utility of colchicine as a drug, its pharmacokinetic (PK) profile is less than ideal with plasma concentration peaking within 30-90 minutes, with a half-life of 1 to 2.7 hours. Additionally, colchicine absorption across the intestinal mucosa is impacted by its ability to depolymerize microtubules within the epithelial cells of the mucosa. This has led to the necessity to establish dosing thresholds in the treatment of gout (dose escalation until GI distress). However, it is the impact on the GI tract that is often dose-limiting in the treatment of chronic diseases. Together, these factors result in large variability in absorption and bioavailability between individuals (24% to 88%; median 45%), which presents challenges in establishing an optimal dosing paradigm in patients. Further complicating the clinical picture is the relatively narrow therapeutic window of colchicine (lethal dose approximately 10 to 30 times therapeutic dose). As such, colchicine dosing is used only acutely in response to gout flare-up, or limited to twice a day dosing. Given the significant clinical potential for microtubule-targeting in DMD, we have recently developed a family of colchicine pro-drugs. These pro-drugs are pharmacologically inactive until they are activated by enzymatic or non-enzymatic hydrolysis in the body. These new pro-drug formulations will allow for more clinically tolerated dosing (once a day for example) and more consistent therapeutic effects at the tissue level (due to increased half-life and a delayed peak plasma concentration). This approach will open novel therapeutic avenues in DMD, as well as chronic diseases that benefit from colchicine therapies, such as Limb Girdle Muscular Dystrophy, sarcopenia, osteoporosis, and atrial fibrillation. Therefore, the goal of this proposal is to test the feasibility of our novel therapy in DMD. In our first aim, we suggest to synthesize and test efficacy and PK of 5 different pro-drugs of colchicine to tailor an ideal PK profile with a lower Cmax than colchicine and increased half-life. In our second aim, we will then test the efficacy of our lead therapeutic in a mouse model of DMD. If shown effective, our drug can be rapidly advanced to IND-enabling studies for use in DMD as part of a Phase II SBIR and represent a new class of drugs for the treatment of neuromuscular disorders.